In recent years, urethane (meth)acrylate resins have been known as waterproofing building materials. Urethane (meth)acrylate resins with improved strength and durability in addition to an elongation percentage and flexibility have been known. (PTL 1)
Since such radical-curable urethane (meth)acrylate resins are used as layers for waterproofing coating films, which have a film thickness of 1 mm or more, the surface-drying property of the radical-curable urethane (meth)acrylate resin are improved by adding a paraffin wax. However, since the temperature varies greatly from season to season, currently, the formulation of paraffin wax and the like is changed from season to season so as to accommodate the seasonal temperature variations. Therefore, a urethane (meth)acrylate resin composition used for a coating material that is free from the surface-drying property at ordinary temperature and pinholes has been demanded.